+(* Advanced inversion lemmas on relocation **********************************)
+
+lemma cny_inv_lift_ge_up: ∀G,L,K,T,U,s,d,dt,e,et. ⦃G, L⦄ ⊢ ▶[dt, et] 𝐍⦃U⦄ → ⇩[s, d, e] L ≡ K →
+ ⇧[d, e] T ≡ U → d ≤ dt → dt ≤ yinj d + e → yinj d + e ≤ dt + et →
+ ⦃G, K⦄ ⊢ ▶[d, dt + et - (yinj d + e)] 𝐍⦃T⦄.
+#G #L #K #T1 #U1 #s #d #dt #e #et #HU1 #HLK #HTU1 #Hddt #Hdtde #Hdedet
+lapply (cny_narrow … HU1 (d+e) (dt+et-(d+e)) ? ?) -HU1 [ >ymax_pre_sn_comm ] // #HU1
+lapply (cny_inv_lift_ge … HU1 … HLK … HTU1 ?) // -L -U1
+>yplus_minus_inj //
+qed-.
+
+lemma cny_inv_lift_subst: ∀G,L,K,V,W,i,d,e. d ≤ yinj i → i < d + e →
+ ⇩[i+1] L ≡ K → ⦃G, L⦄ ⊢ ▶[d, e] 𝐍⦃W⦄ →
+ ⇧[O, i+1] V ≡ W → ⦃G, K⦄ ⊢ ▶[O, ⫰(d+e-i)] 𝐍⦃V⦄.
+#G #L #K #V #W #i #d #e #Hdi #Hide #HLK #HW #HVW
+lapply (cny_inv_lift_ge_up … HW … HLK … HVW ? ? ?) //
+>yplus_O1 <yplus_inj >yplus_SO2
+[ /2 width=1 by ylt_fwd_le_succ1/
+| /2 width=3 by yle_trans/
+| >yminus_succ2 //
+]
+qed-.
+